Vernier voltage regulator

ABSTRACT

A split, tapped transformer winding and a current limiting reactor are connected between the two movable fingers of a conventional tap changer. Contacts of a second tap changer are coupled to the taps of the split transformer winding and to the center tap of the equalizing reactor, and engaged by two movable fingers for providing a vernier adjustment of output voltage.

United States Patent Inventor James W. Simpson Plttslleld, Mass.

June 25, 1970 Nov. 9, 1971 General Electric Company Appl. No. FiledPatented Assignee VERNIER VOLTAGE REGULATOR 7 Claims, 2 Drawing Figs.

US. Cl 323/435 R, 336/150 Int. Cl. 1-l02pl3/ll6,

m 6051 1/14 Field of Search 323/435 R,

References Cited UNITED STATES PATENTS 1,905,249 4/1933 Snyder 323/435 R3,365,655 1/1968 Simpson et al... 323/435 R 3,423,668 1/1969 Brennan323/435 R 3,100,865 8/1963 Nielsen 323/435 R Primary Examiner-GeraldGoldberg Attorneys-Francis X. Doyle, Vale P. Myles, Frank L.

Neuhauser, Oscar B. Waddell and Joseph B. Forman ABSTRACT: A split,tapped transformer winding and a current limiting reactor are connectedbetween the two movable fingers of a conventional tap changer. Contactsof a second tap changer are coupled to the taps of the split transformerwinding and to the center tap of the equalizing reactor, and

' engaged by two movable fingers for providing a vernier adjustment ofoutput voltage.

1 vaanma VOLTAGE REGULATOR BACKGROUND OF THE INVENTION The presentinvention relates to voltage regulators, and, more particularly, tostep-type regulators wherein coarse and vernier tap windings areprovided.

Voltage regulators are often utilized to maintain line voltages at somepredetermined level, and also to provide a source of voltage which maybe purposely varied over a given range. In order to prevent grossdisturbances on the line and to provide, within very close limits, avoltage which is desired, it is necessary to be able to apply thevoltage in very small, regulated increments. At the same time, shouldthe demand for voltage change radically, it is necessary to rapidlychange the applied voltage in order to meet the new requirements. Toful' fill such requirements requires voltage regulators which have meansto vary supply voltages over large increments, usually by meansofstep-type regulators coupled to tapped transformer windings. Toprovide small incremental voltage changes, such regulators often have avernier control which provides a further series of incremental stepssuperimposed upon the first-mentioned coarse steps.

The combination of vernier and coarse-step-type regulators is well knownin the art, one example being U.S. Pat. No. 3,365,655 Simpson et al.,issued Jan. 23, 1968 and assigned to the assignee of the presentinvention. In such mechanisms, at first transformer is provided with awinding having a plurality of tap sections, each section being connectedto one of a plurality of separate, spaced contacts disposed in acircular configuration. A pair of rotatable fingers are provided toengage a single contact, or a pair of adjacent contacts, and a currentequalizing reactor connected between the fingers, When both fingers areat a common contact, each finger passes substantially the same current,and the equal currents flow through the center tap of the equalizingreactor to a load. However, when the fingers bridge a pair of contactswhich are at different voltages, the reactor prevents the shortcircuiting of the two fingers and thus the passage of destructively highcirculating current therethrough, while presenting little impedance tothe passage of load current.

According to the prior art, when a vernier adjustment is required asecond transfonner may be connected across the aforementioned fingers inorder to provide both the reactance necessary to reduce circulatingcurrents to an acceptable level in lieu of an equalizing reactor, and toprovide a plurality of tap sections which are coupled to the contacts ofa vernier tap changer. The vernier tap changer is then adjusted toselect the voltage desired, within the range made available by a firstcoarse tap changer. To prevent destructive circulating currents in thevernier transformer winding segments, a limiting reactor is connnectedbetween the fingers of the vernier tap changer.

Unfortunately, however, such arrangements have certain disadvantagesinherent in their design. Should the vernier transformer winding be acontinuous one, the impedance of such winding would rarely be matched tothat of the transformer segments, as is the case of a single purposecurrent limiting reactor. Further, no matter to which segment thevernier tap changer is connected, some load current would be drawnthrough both fingers of the coarse tap changer. In such a case, it wouldbe impossible to move either finger of the coarse tap changer from onetap segment to another without breaking a substantial portion of theload current. One way to circumvent this problem is to remove thevernier winding from the conductive path, and insert a suitable limitingreactor while the coarse tap changer is being moved. However, with thisscheme the load might be temporarily removed from the line, and in anycase extra switching mechanisms are required. Further, the additionalsteps necessitate unwanted delay. On the other hand, should the limitingreactor be placed in shunt with the vernier winding, the continuousvernier winding would pass the circulating currents which limitingreactor is interided to restrict.

To obviate these difficulties, it has been suggested that a split typevernier winding be provided. By counter winding the two halves, andbridging the split-apart ends by the fingers of the vernier tap changer,a limiting reactor will be constituted which is disposed between thefingers of the coarse tap changer. The reactor consists of the seriescombination of a first portion of the split vernier winding, a firstvernier finger, the vernier tap changer limiting reactor, a secondvernier finger, and the second portion of the split vernier winding.Such an arrangement, however, compromises the design of one or both ofthe vernier tap winding and the vernier limiting reactor. In addition,it necessitates the moving of the vernier contacts to a particularposition before a finger of the coarse tap changer may be moved to a newcontact.

A still further device, embodied in the above-mentioned Simpson et.211., patent, provides a limiting reactor permanently placed across thetwo fingers of the coarse tap changer. The center tap of the reactor iscoupled to one of the stationary contacts of the vernier tap changer. Atransformer winding having a plurality of output taps thereon is placedin parallel with the limiting reactor and the taps are connected to theremaining stationary contacts of the vernier tap changer. The fingers ofthe vernier tap changer must be moved to a position wherein they areboth coupled to the center tap of the aforementioned current limitingreactor before the coarse tap changer may be moved. While thisarrangement has advantages not previously found in the art, it stillprovides an inductive winding in parallel with the current limitingreactor, and necessitates the movement of the fingers of a vernier tapchanger to a single, predetermined position before a coarse tap changermay be adjusted.

SUMMARY OF THE INVENTION The present invention contemplates theprovision of a cur rent limiting reactor connected between the fingersof a coarse tap changer, the contacts of which are coupled to tapsections of a transformer. A first inductive winding is provided inbucking relationship to the transformer winding engaged by the coarsetap changer, and one end of said inductive winding is connected directlyto a first finger of the coarse tap changer. A second, boostinginductive winding is provided, one end of which is connected directly tothe second finer of the coarse tap changer. Both the bucking andboosting windings are divided into a plurality of tap segments, each ofthe segments being connected to a stationary contact of a vernier tapchanger. The center tap of the current limiting reactor is connected toa further stationary contact of the vernier tap changer. When thefingers of the coarse tap changer are located on a common stationarycontact, the voltage obtained thereby may be provided to the vernier tapchanger by means of the aforementioned center tap on the limitingreactor. Higher voltages in small increments are provided by theboosting tap winding and lower voltages by the bucking tap winding.When, however, the fingers of the coarse tap changer are positioned soas tobridge a pair of adjacent contacts, the current limiting reactorconducts the resulting circulating current, unaffected by the bucking orboosting windings. The bucking vernier winding thus provides the verniertap selector with voltages which incrementally decrease from that of thehigher voltage finger, while the boosting winding provides voltageswhich incrementally increase from that of the lower voltage finger. inaddition, the center tap of the limiting reactor provides the verniertap changer with a voltage which is halfway between thosevoltagesencountered by the fingers of the coarse tap changer.

While it will be seen that the arrangement so far described provides avernier regulator without the disadvantage of incor porating a limitingreactor which is mismatched to the coarse tap winding characteristics,still further advantages inhere.

While it is desirable that the contacts of the vernier voltage regulatorbe positioned on the contact coupled to the center tap of the currentlimiting reactor when both fingers of the coarse tap changer are totraverse more than one contact, it is not necessary for the vemier tapchanger to be so oriented for all adjustments of the coarse tap changerfingers. It will be seen, for instance, that if the fingers of thevernier tap changer are in engagement with contacts connected to thathalf of the vemier winding which is coupled to a first coarse tapchanger finger, the only current which then flows through the secondcoarse tap changer finger is the circulating current from the coarsetransformer winding itself. The second coarse tap changer finger, nowconducting minimal current, may then be transferred to another contactwithout having to break any portion of the load current. The advantagesfrom this arrangement are twofold. Firstly, arcing from the transferredfinger is practically eliminated, thus greatly increasing the life ofthe finger and contacts. Secondly, it will be understood that in orderto provide such a condition, the fingers of the vemier tap changer needonly be in contact with that half of the vernier winding which is notcoupled to the advancing finger. Since the contacts connected to thewinding will comprise one half of all the contacts of vemier tapchanger, less that one connected to the center tap of the currentlimiting reactor, in many cases the vemier tap changer will already bein a suitable position when such a coarse adjustment is necessary.Further, should the vemier fingers be coupled through a vemier windingto a coarse tap changer finger which is to be transferred to a newcontact, it will only be necessary to move the vemier fingers to thenearest contact which is coupled to the other vemier winding. Relocationof the vemier fingers is thus not nearly as critical as in the priorart, facilitating a much more rapid response of the coarse tap changermechanism.

It is thus an object of the present invention to provide a vemiervoltage control whereby only a current limiting reactor is in seriesconnection between the fingers of a coarse tap changer.

it is a further object of this invention to provide a step type voltageregulator in which a vernier tap changer need not be located on aparticular contact before a coarse tap changer may be moved.

It is a further object of this invention to provide, in a verniervoltage regulator, a vemier tap winding employing substantially lessmaterial than prior devices.

BRIEF DESCRIPTION OF THE DRAWINGS While the specification concludes withclaims particularly pointing out and distinctly claiming the subjectmatter which is regarded as the invention, it is believed that theinvention will be better understood from the following description ofthe preferred embodiment, taken in connection with the accompanyingdrawings, in which:

FIG. 1 is a schematic circuit diagram of a voltage regulator having avemier control according to one embodiment of this invention;

FIG. 2 is a schematic circuit diagram of a modified form of the voltageregulator of FIG. 1 incorporating a reversing switch.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The voltage regulator of thisinvention will be described with particular reference to the drawing,wherein like numerals are used to indicate like parts throughout thevarious figures. Considering first FIG. i, there is shown a transformerT, having a tap winding indicated at 10. The winding as shown is dividedinto six equal tap sections which are connected to circularly arrangedstationary contact members 1211-12! of a coarse tap changer 12. As willbe understood by those skilled in the art, winding 10 is used to providevoltage differentials whereby large changes in voltage output may beobtained by selecting appropriate taps. Of course, it will be understoodthat any convenient number of tap sections can be used, six being shownfor purposes of illustration. Coarse tap changer 12 further lncludes apair of radially extending contact fingers A and B. The fingers areelectrically separate, and the distance between their extremities issomewhat less than the width of stationary contacts l2a-l2f, but greaterthan the distance between the contacts. Fingers A and B may thus bothconnect to a common contact, or alternatively may connect to adjacentcontacts. Connected between the fingers is a first current limitingreactor 13 having a center tap, as is well known in the art. Thelimiting reactor comprises the only electrical path existing betweenfingers A and B, and prevents excessive current from circulating betweenadjacent tap segments when fin gers A and B lie on different contacts,while allowing current to pass through its center tap to a load withvirtually no impedance thereto.

Coupled to either end of first limiting reactor 13 are a pair ofwindings l4 and 15 which together comprise what will be referred to asthe split vemier winding of the regulating system. Windings l4 and 15are each divided into a like number of tap segments, each segment beingcoupled to a stationary contact 16a-16f of a vemier tap changergenerally indicated at 16. Again, it will be understood that anyconvenient number of vemier taps may be provided. The remaining contact17 of the vemier tap changer is coupled directly to the center tap ofcurrent limiting reactor 13. As in the case of the coarse tap changer, apair of radially extending fingers C and D are provided to engage thestationary contacts. Fingers C and D are electrically connected by meansof a second center taped limiting reactor indicated at 19 which preventsexcessive currents from circulating through the tap sections of windings14 and 15. Output voltage is applied to a load (not shown) connectedacross output temtinals 21 and 22. Control means 20 operates to rotatethe tap changers l2 and 16 in a manner that will hereinafter bedescribed.

OPERATION The operation of the embodiment shown in FIG. I will now bedescribed. To bring the output of the voltage regulator into the generalrange required, fingers A and b of coarse tap changer 12 are rotated toa position where they connect with a suitable contact or contacts ofcoarse winding 10. Fingers C and D of vemier tap changer 16 are thenrotated until they encounter that contact or contacts which provide thedesired output voltage at the center tap of second current limitingreactor 19. Should fingers A and B of coarse tap changer l2 lie upon acommon contact, contact 17 would provide that identical voltage to thevemier tap changer, while contacts 16a, 16b, and 16c of bucking winding14 would provide incrementally decreasing voltages, and contacts 16d,16c, and 16] of boosting winding 15 would provide incrementallyincreasing voltages. Since windings l4 and 15 are split, when fingers Cand D of vemier tap changer 16 are coupled to contacts 16d, 16e, 16fsubstantially all load current will flow through finger B. Similarly,should fingers C or D connect to contacts 16c, 16b, or Me, load currentwould be drawn through finger A.

If it is now desired to rotate fingers A and B of coarse tap changer 12from a common contact, for instance 12], to bridge a pair of consecutivecontacts 12c and 12f, it is apparent that finger B must leave the commoncontact, traverse a gap, and connect with a new contact. Should thatfinger have been carrying a substantial current, when it breaks contactwith contact 12f arcing will occur with detrimental effects to both thefinger and the contact from which the arc is drawn. lt is thus desirablethat load current be drawn from finger A while the tap selector isactuated. This condition is effected in the following manner. Assumingthat fingers A and B are initially located on contactor 12f, shouldfingers C or D of vernier tap changer i6 connect with contactors 16d,16, or f load current will be drawn through finger B. When it is desiredto move finger B to contact 12c, fingers C and D of vemier tap changer16 are first rotated so that they connect with segments 16a, 16b, or 16c. Full load current is now drawn through finger A of coarse tap changer12, the current through finger B being only that circulating currentwhich is passed by first limiting reactor 13. Tap changer 12 may now berotated in a counterclockwise direction so as to cause finger B todisengage contact 12f and engage contactor 12c. Should the outputvoltage provided at the center tap of second limiting reactor 19 nowrequire further, finger adjustment, this can be provided by locatingfingers C and D on the appropriate contacts of vernier tap changer 16.

In some cases, however, it is necessary that gross changes, hereinconsidered to be changes of more than one coarse tap segment, are to bemade. Obviously load current cannot be removed from both fingers A and Bof coarse tap changer 12 without opening the circuit, or providing aseparate shunt contactor. Should the fingers of vernier tap changer 16connect to either winding 14 or 15, full load current would then bedrawn through one of the fingers A or B resulting in detrimental arcingwhen that finger moves from one contact to the next. To balance thecurrent drawn through fingers A and B, fingers C and D are connected tocontact 17 of the vernier tap changer. Full load current is now drawnentirely from the center tap of first limiting reactor 13, and thecurrents flowing through fingers A and B of tap changer 12 areconstrained to be equal. Fingers A and B may now be rotated to thedesired contact with minimal arcing.

As will be understood by those skilled in the art, rotating mechanism 20may advantageously include a latching device for preventing the rotationof coarse tap changer 12 when the fingers of vernier tap changer 16 arein a disadvantageous position. For instance, when it is desired to movefinger B of tap changer 12 from a common contact with finger Acounterclockwise to a new contact, a simple latch may be provided whichprevents such counterclockwise movement until fingers C and D of verniertap changer 16 rest upon contacts 16a, 16b, and 160. Further, a secondlatch would prevent gross changes, i.e., a movement greater than thedistance between consecutive contacts, of fingers A and B until fingersC and D of vernier tap changer 16 rest upon contact 17. It will beobvious to those skilled in the art that an almost limitless number ofsimple latching mechanisms may be adapted to prevent unwanted motion oftap changer 12 until the fingers of tap changer 16 are in a desiredposition, and the foregoing example is only one embodiment of such adevice. Alternatively, a plurality of electrical switches may beprovided to prevent the energization of means driving tap changer 12unless tap changer 16 were in a desired position.

Regardless of the embodiment utilized for rotating mechanism 20, it willbe seen that the orientation of fingers C and D of vernier tap changer16 for small movements of coarse tap changer 12 is far less criticalthan in the devices taught by the prior art. Fingers C and D of verniertap changer 16 should advantageously rest upon contacts connected to thesplit winding which is coupled to the finger of the coarse tap changerremaining upon its contact while the other finger jumps to a newcontact. In such a case it is also feasible, however, to positionfingers C and D on contact 17, so as to draw equal current from fingersA and B. It will thus be seen that it is possible to have fingers C andD lying on one of more than half of the available contacts of thevernier tap changer when providing single step adjustments in coarse tapchanger 12. Due to the less critical positioning of the vernier tapchanger fingers, it will oftentimes not be necessary to move tap changer16 at all before initiating movement of coarse tap changer 12. If it isnecessary to relocate fingers C and D of the vernier tap changer tocontacts coupled to the opposite split winding, it will be seen that anarc of 90 or less is all that need be traversed by the fingers.

A further benefit flows from the split winding configuration used withthe vernier tap changer. It will be seen from the embodiment disclosedin FIG. 1 that a total of seven taps are provided by the vernier tapchanger through the provision of a total of only 4 tap sections, twosuch tap sections on each half 14 and 15 of the split winding. It willbe understood by those skilled in the art that in general (n-l tapwinding sections are necessary to provide mn taps. However, in thepresent case,

only (It-3) sections are necessary to provide the n taps desired. In thepresent case, for example, to provide the seven taps desired a total ofsix sections of winding would be required according to the prior art,while in fact only 4 are utilized with the split winding of the instantinvention; a saving of 33 percent in material.

It will be recognized that it is possible to place windings l4 and 15 ona common core with coarse winding 10. While a saving would thus resultin the increased utilization of core material, the incremental voltageavailable from windings I4 and 15 would be limited by the volts/turnratio of transformer T By placing windings l4 and 15 on an independentcore, however, this restriction is avoided and a greater flexibility involtage steps is provided at the cost of additional core material.

Referring now to FIG. 2, a further embodiment of the present inventionis shown which provides for an even more efficient utilization ofmaterial. A single vernier tap winding 23 is provided, which mayadvantageously correspond in size and type to windings 14 or 15 of FIG.I. The taps of windings 23 are coupled to stationary contacts 24a-24d ofvernier tap changer 24. A first end of winding 23 is connected to fingerA of coarse tap changer 12 through contacts 26 of a double pole, singlethrow switch generally indicated at 28. In this mode, winding 23 may beconsidered to be in boosting relationship the tap upon which finger Arests. When switch 28 is moved to its opposite position, contacts 27 areclosed, and contacts 26 are simultaneously opened. The second end ofwinding 23 is now connected to finger B of coarse tap changer I2, inbucking or substractive relationship thereto. Before a finger is movedso as to disengage it from the contact upon which it then rests, switch28 is actuated to couple winding 23 to the other finger, causing thefirst mentioned finger to be relieved of load current.

Similarly, before gross changes whereby fingers A and B both engage anddisengage contacts may be made, fingers C and D of vernier tap changer24 must be positioned so as to rest upon contact 25 corresponding to thecenter tap of current equalizer 13. As in the embodiment describedabove, a latching mechanism may be provided within rotating mechanism 20to allow gross changes of coarse tap changer 12 only when vernier tapchanger 24 is in this position.

In addition, a similar latching arrangement may be provided wherebyswitch 28 is allowed to change position only when fingers C and D ofvernier tap changer 24 are in communication with contact 25. In thismanner, load current is never interrupted and the proper switchingsequency is ensured.

As described with regard to the embodiment of FIG. I, vernier tapwinding 23 may be placed on a common core with coarse tap winding 10 oralternatively, may be placed upon a separate core. In either case, onlyhalf as much winding material is required than is the case with thevernier winding of FIG. 1.

From the above, it will be clear that by means of this invention thereis provided a voltage regulator having vernier voltage control in whichcoarse voltage changes may be made without interrupting the circuitprovided thereby. Further, coarse voltage changes may be made duringwhich load current is removed from one finger of a tap changer beforecausing said finger to move to a ditferent contact. In addition, a

circuit has been taught which provides a separate tap vernier winding inconjunction with a coarse tap changer, without comprising the design ofthe current limiting reactor connected between fingers of the coarse tapchanger.

While there has been shown and described presently preferred embodimentsof this invention, it will of course be understood that various changesmay be made in structural details without departing from the spirit andscope of the invention, particularly as set forth in the appendedclaims.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

l. A voltage regulator comprising: a. first induction means having awinding divided into a plurality of tap sections;

b. first tap changer means including a first plurality of spacedcontacts, each of said first spaced contacts being connected to one ofsaid plurality of tap sections, and further including a first pair ofmovable fingers for engaging said contacts, said fingers being movablein unison and spaced so that at least one of said fingers will alwaysengage at least one contact;

c. first current limiting reactor means including a winding connectedbetween said first pair of fingers and having a tap at the center ofsaid winding;

d. second induction means comprising two individual windings, each ofsaid windings being divided into a plurality of tap sections, each ofsaid windings being connected to a different one of said movable fingersof said first tap changer means;

' e. second tap changer means including a second plurality of spacedcontacts, one of said second spaced contacts being connected to said tapat the center of said first current limiting reactor winding, the restof said contacts being connnected to said plurality of tap sections ofsaid second induction means, and further including a second pair ofmovable fingers for engaging said contacts, said fingers being movablein unison and spaced so that at least one of said fingers will alwaysengage at least-one of said second spaced contacts; and

second current limiting means including a winding connected between saidsecond fingers and having a tap at the center of said winding.

2. A voltage regulator as recited in claim 1 wherein said first and saidsecond induction means are disposed on a common magnetic core.

3. A voltage regulator as recited in claim 1, further including meansfor preventing said first fingers of said first tap changer means fromtraversing more than one of said first spaced contacts when said secondfingers of said second tap changer means are not disposed upon said oneof said second spaced contacts which is connected to said tap at thecenter of said first current limiting reactor winding.

4. A voltage regulator as recited in claim I, further including meansfor preventing either of said first fingers of said first tap changermeans from disengaging one of said first spaced contacts when either ofsaid second fingers of said second tap changer means is coupled to thatwinding of said second induction means which is connected to thedisengaging finger.

S. A voltage regulator comprising:

a. first induction means having a winding divided into a plurality oftap sections;

b. first tap changer means including a first plurality of spacedcontacts, each of said first spaced contacts being connected to one ofsaid plurality of tap sections, and further including a first pair ofmovable fingers for engaging said contacts, said fingers being movablein unison and spaced so that at least one of said fingers will alwaysengage at least one contact;

c, first current limiting reactor means including a winding connectedbetween said first pair of fingers and having a tap at the center ofsaid winding;

. second induction means including a second winding having a first and asecond end and being divided into a plurality of tap sections;

. switch means for selectively connecting said first or said second endofsaid second winding to predetermined ones of said first pair ofmovable fingers of said first tap changer means;

f. second tap changer means including a second plurality of spacedcontacts, one of said second spaced contacts being connected to said tapat the center of said first current limiting reactor winding, the restof said contacts being connected to said plurality of tap sections ofsaid second induction means, and further including a second pair ofmovable fingers for engaging said contacts, said fingers being movablein unison and spaced so that at least one of said fingers will alwaysengage at least one of said second spaced contacts; and t second currentlimiting means including a winding connected between said second fingersand having a tap at the center of said winding.

6. A voltage regulator as recited in claim 5 wherein said first and saidsecond induction means are disposed on a common magnetic core.

7. A voltage regulator as recited in claim 5, further including meansfor preventing said first fingers of said first tap changer means formtraversing more than one of said first spaced contacts when said secondfingers of said second tap changer means are not disposed upon said oneof said second spaced contacts which is connected to said tap at thecenter of said first current limiting reactor winding.

a i a: k a

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 9,7Dated November 9, 1971 Inventor( James w. Simpson It is certified thaterror appears in the aboveidentified patent and that said Letters Patentare hereby corrected as shown below:

Col. 1, line 74 After "which" insert the Col. 2, line M "finer" shouldbe finger Col. t, line 27 "taped" should be tapped Col. 4, line 69 "1""should be 16f Col. 5, line 75 "mn" should be n Col. 8, line 39 "form"should be from Signed and sealed this 20th day of June 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSGHALK Attesting Officer Commissionerof Patents

1. A voltage regulator comprising: a. first induction means having awinding divided into a plurality of tap sections; b. first tap changermeans including a first plurality of spaced contacts, each of said firstspaced contacts being connected to one of said plurality of tapsections, and further including a first pair of movable fingers forengaging said contacts, said fingers being movable in unison and spacedso that at least one of said fingers will always engage at least onecontact; c. first current limiting reactor means including a windingconnected between said first pair of fingers and having a tap at thecenter of said winding; d. second induction means comprising twoindividual windings, each of said windings being divided into aplurality of tap sections, each of said windings being connected to adifferent one of said movable fingers of said first tap changer means;e. second tap changer means including a second plurality of spacedcontacts, one of said second spaced contacts being connected to said tapat the center of said first current limiting reactor winding, the restof said contacts being connnected to said plurality of tap sections ofsaid second induction means, and further including a second pair ofmovable fingers for engaging said contacts, said fingers being movablein unison and spaced so that at least one of said fingers will alwaysengage at least one of said second spaced contacts; and f. secondcurrent limiting means including a winding connected between said secondfingers and having a tap at The center of said winding.
 2. A voltageregulator as recited in claim 1 wherein said first and said secondinduction means are disposed on a common magnetic core.
 3. A voltageregulator as recited in claim 1, further including means for preventingsaid first fingers of said first tap changer means from traversing morethan one of said first spaced contacts when said second fingers of saidsecond tap changer means are not disposed upon said one of said secondspaced contacts which is connected to said tap at the center of saidfirst current limiting reactor winding.
 4. A voltage regulator asrecited in claim 1, further including means for preventing either ofsaid first fingers of said first tap changer means from disengaging oneof said first spaced contacts when either of said second fingers of saidsecond tap changer means is coupled to that winding of said secondinduction means which is connected to the disengaging finger.
 5. Avoltage regulator comprising: a. first induction means having a windingdivided into a plurality of tap sections; b. first tap changer meansincluding a first plurality of spaced contacts, each of said firstspaced contacts being connected to one of said plurality of tapsections, and further including a first pair of movable fingers forengaging said contacts, said fingers being movable in unison and spacedso that at least one of said fingers will always engage at least onecontact; c. first current limiting reactor means including a windingconnected between said first pair of fingers and having a tap at thecenter of said winding; d. second induction means including a secondwinding having a first and a second end and being divided into aplurality of tap sections; e. switch means for selectively connectingsaid first or said second end of said second winding to predeterminedones of said first pair of movable fingers of said first tap changermeans; f. second tap changer means including a second plurality ofspaced contacts, one of said second spaced contacts being connected tosaid tap at the center of said first current limiting reactor winding,the rest of said contacts being connected to said plurality of tapsections of said second induction means, and further including a secondpair of movable fingers for engaging said contacts, said fingers beingmovable in unison and spaced so that at least one of said fingers willalways engage at least one of said second spaced contacts; and g. secondcurrent limiting means including a winding connected between said secondfingers and having a tap at the center of said winding.
 6. A voltageregulator as recited in claim 5 wherein said first and said secondinduction means are disposed on a common magnetic core.
 7. A voltageregulator as recited in claim 5, further including means for preventingsaid first fingers of said first tap changer means form traversing morethan one of said first spaced contacts when said second fingers of saidsecond tap changer means are not disposed upon said one of said secondspaced contacts which is connected to said tap at the center of saidfirst current limiting reactor winding.